Light-hole contribution to noise and diffusion in p-type germanium at low temperatures

The aim of this paper is to investigate noise and diffusion for fields that show the diffusion-to-streaming transition. A Monte Carlo (MC) computation of the drift velocity, mean energy, diffusion constant, and of the velocity-velocity correlation function C() is presented for p-type germanium at low temperatures (4 K). Analytical results for streaming are reviewed. The MC computations for the case that only heavy holes are involved, in the presence of acoustical-phonon scattering and impurity scattering, in addition to the optical-phonon emission responsible for streaming, indicate that C(,,) damps out for large; the diffusivities D and D? are in agreement with previous results. However, the MC computations when the contribution of the light holes is included (not considered before), involving the movement of two species as well as interband transitions, show that the streaming behavior and the associated diffusion coefficient are very substantially changed from the one-band results. The D? is dominated by transitions, and C() shows quasiperiodicity with about one-third of the heavy-holes streaming period, i.e., 0/3.